14 CFR § 121.356 - Collision avoidance system.

---
identifier: "/us/cfr/t14/s121.356"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "14 CFR § 121.356 - Collision avoidance system."
title_number: 14
title_name: "Aeronautics and Space"
section_number: "121.356"
section_name: "Collision avoidance system."
chapter_name: "FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
subchapter_number: "G"
subchapter_name: "AIR CARRIERS AND OPERATORS FOR COMPENSATION OR HIRE: CERTIFICATION AND OPERATIONS"
part_number: "121"
part_name: "OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 106(f), 40103, 40113, 40119, 41706, 42301 preceding note added by Pub. L. 112-95, sec. 412, 126 Stat. 89, 44101, 44701-44702, 44705, 44709-44711, 44713, 44716-44717, 44722, 44729, 44732; 46105; Pub. L. 111-216, 124 Stat. 2348 (49 U.S.C. 44701 note); Pub. L. 112-95, 126 Stat. 62 (49 U.S.C. 44732 note); Pub. L. 115-254, 132 Stat. 3186 (49 U.S.C. 44701 note)."
cfr_part: "121"
---


# 121.356 Collision avoidance system.

Effective January 1, 2005, any airplane you operate under this part must be equipped and operated according to the following table:

Collision Avoidance Systems

| If you operate any— | Then you must operate that airplane with— |
| --- | --- |
| (a) Turbine-powered airplane of more than 33,000 pounds maximum certificated takeoff weight | (1) An appropriate class of Mode S transponder that meets Technical Standard Order (TSO) C-112, or a later version, and one of the following approved units:(i) TCAS II that meets TSO C-119b (version 7.0), or takeoff weight a later version. |
|  | (ii) TCAS II that meets TSO C-119a (version 6.04A Enhanced) that was installed in that airplane before May 1, 2003. If that TCAS II version 6.04A Enhanced no longer can be repaired to TSO C-119a standards, it must be replaced with a TCAS II that meets TSO C-119b (version 7.0), or a later version.(iii) A collision avoidance system equivalent to TSO C-119b (version 7.0), or a later version, capable of coordinating with units that meet TSO C-119a (version 6.04A Enhanced), or a later version. |
| (b) Passenger or combination cargo/passenger (combi) airplane that has a passenger seat configuration of 10-30 seats | (1) TCAS I that meets TSO C-118, or a later version, or(2) A collision avoidance system equivalent to has a TSO C-118, or a later version, or(3) A collision avoidance system and Mode S transponder that meet paragraph (a)(1) of this section. |
| (c) Piston-powered airplane of more than 33,000 pounds maximum certificated takeoff weight | (1) TCAS I that meets TSO C-118, or a later version, or(2) A collision avoidance system equivalent to maximum TSO C-118, or a later version, or(3) A collision avoidance system and Mode S transponder that meet paragraph (a)(1) of this section. |

[Docket FAA-2001-10910, 68 FR 15902, Apr. 1, 2003]